1. Field of the Invention
This invention relates to pneumatic tires for use on offroad vehicles, and more particularly to improved pneumatic tires especially suitable for use on all terrain-type vehicles.
2. DESCRIPTION OF THE PRIOR ART
Pneumatic tires designed primarily for offroad vehicles are well known and normally incorporate a tread designed to provide high traction in soft ground such as frequently encountered by farm tractors, graders and other heavy equipment. Such tread designs conventionally employ a system of elongated lugs emanating from each lateral edge of the tread and extending to a position near the vertical centerplane of the tire, with the lugs emanating from opposite sides of the tire cooperating to form a generally herringbone tread pattern. To provide the necessary traction for operating heavy equipment and pulling heavy loads, the lugs are relatively deep and designed to bite into the ground surface. The generally herringbone arrangement of the lugs tends to expel the earth laterally of the tire to facilitate the biting action and prevent the lugs from filling with earth and losing traction. Examples of such known tread designs may be found in U.S. Pat. Nos. 4,791,971; 4,534,392; 4,480,622; and 4,383,567.
While all terrain vehicles (ATVs) are normally operated off the road, their relatively light weight and low center of gravity, as well as their speed of operation and maneuverability, make the known tractor tire tread designs such as those disclosed in the above U.S. patents generally unsatisfactory for use on such vehicles. Although effective straightline or drawbar traction is required to enable an ATV to traverse rough and hilly terrain as well as mud, sand and snow, substantial lateral traction is also required to enable maneuverability of the vehicle. Further, minimum power or pulling traction, or even braking is frequently employed during maneuvering when maximum lateral traction is required for vehicle stability. Conventional off road tractor tire tread designs are particularly ineffective in providing lateral stability during low wheel torque or braking, and during maneuvering. It is, therefore, an object of the present invention to provide an improved pneumatic tire for use on off-the-road vehicles.
Another object is to provide an improved pneumatic tire having improved traction characteristics for enhanced pulling and for maneuvering of off-the-road vehicles.
Another object is to provide a pneumatic tire particularly useful for ATVs and having an improved tread design which provides both improved drawbar traction and lateral stabilization or traction during maneuvering.